Brant A. Gardner argues that "gold and silver" is an idiom conveying the meaning of "everything necessary," and should not be taken literally.
Brant A. Gardner, Second Witness: Analytical and Contextual Commentary on the Book of Mormon, 6 vols. (Salt Lake City: Greg Kofford Books, 2007), 4: 266-67
Mormon further characterizes the Lamanites as greedy: “their hearts were set upon riches, or upon gold and silver, and precious stones.” Mesoamerican tribute lists include gold and silver. When they include precious stones, it was typically jade (semi-precious) rather than the Western precious stones as emeralds, rubies, and diamonds. The Book of Mormon frequently mentions “gold and silver” as a synonym for desiring wealth. Mesoamerican cultures did not value either gold or silver as highly as Westerners who explored, conquered, looted, and plundered in the search of those meals . . . I hypothesize that “gold and silver” is a phrase with an idiomatic, rather than literal, meaning—in this case, greed for wealth. A parallel English expression is acquiring a property “lock, stock, and barrel.” Someone has purchased real estate and all that is on it including buildings and natural resources. However, the idiom did not originally apply to land at all, but rather to parts of a rifle.
Similarly, when we go to a sporting goods store to be outfitted for golf, we purchase “the whole enchilada.” Of course, golf clubs, balls, shoes, gloves, and cap have nothing to do with food, let alone Mexican food. The idiom has transcended its literal meaning to convey “everything necessary” to play golf. “Gold and silver” seems to have become a set phrase in the same way. I suspect that Joseph Smith introduced the phrase during his translation. However, I also suspect that John L. Sorenson would suggest that it might be part of the plate language, based on his reading of the linguistic labeling issue of Book of Mormon fauna where he and I have a similar difference of opinion.